The Extension services of Washington State University, Oregon State University, and the University of Idaho established Pacific Northwest Extension Publishing (PNW Publishing) in 1946 as a mechanism of regional cooperation and cost savings. Other regions followed suit in the decades that followed. Today, PNW Publishing is the last standing regional publishing cooperative in Extension. This article identifies factors that have contributed to the success of PNW Publishing and offers lessons that can be applied to other multi-state cooperative efforts in today's Extension environment. [This article was edited by Diane Noel.]